I read with interest the case report by von Guionneau and Stone detailing management of a pregnant woman with limb-girdle muscular dystrophy type 2i (LGMD2i).1 Although monitoring of respiratory function in the second half of pregnancy in these women is mentioned in this case report, it is not given the emphasis that it warrants, given the frequency at which diaphragmatic weakness and sleep apnoea occur in this disorder.2–5 The latter is not specific to LGMD2i, indeed sleep-disordered breathing is seen not uncommonly in individuals with myotonic dystrophy, Duchenne muscular dystrophy, Becker muscle dystrophy and fascioscapulohumeral dystrophy.
Assessment of these women to ensure early detection of abnormalities, particularly of nocturnal respiratory failure, is therefore crucial. The authors mention lung function tests, but I think it is important to highlight that these should be performed supine as well as sitting. Two studies demonstrated a significant reduction in FVC in 12 of 32 (38%) non-pregnant women with LGMD2i in the supine position compared with sitting.3,6
Non-invasive ventilation is a key treatment for those individuals with respiratory failure as a result of this condition. In a combined group of 27 patients with congenital muscular dystrophy and LGMD2i, 14 individuals (52%) had either nocturnal or diurnal hypercapneic respiratory failure.7
Importantly, a normal arterial blood gas analysis during the day does not exclude this diagnosis, as 10 patients with normal daytime PaCO2 had nocturnal hypercapneic respiratory failure. Transcutaneous CO2 capnography/polysomnography can be performed if hypoventilation is suspected. Elevated serum bicarbonate is suggestive of nocturnal hypercapnia.
An additional consideration at delivery is to ensure these women are closely observed while receiving magnesium sulphate, as this has been reported to result in respiratory compromise in neuromuscular disorders.8 Continuous transcutaneous PCO2 and PO2 monitoring is not yet available in all centres, but this is likely to be increasingly used in the future during labour and delivery to monitor these women.
References
- 1.von Guionneau AB, Burford C andStone S.. Obstetric management of a woman with limb-girdle muscular dystrophy type 2i and dilated cardiomyopathy. Obstet Med 2018; 0(0): 1–3. Available at: https://doi-org.ezproxy.library.uq.edu.au/10.1177/1753495X18814622 (accessed 1 April 2019). [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Shahrizaila N, Kinnear WJ, Wills AJ. Respiratory involvement in inherited primary muscle conditions. J Neurol Neurosurg Psychiatry 2006; 77: 1108–1115. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Poppe M, Bourke J, Eagle M, et al. Cardiac and respiratory failure in limb-girdle muscular dystrophy 2I. Ann Neurol 2004; 56: 738–741. [DOI] [PubMed] [Google Scholar]
- 4.Boito CA, Melacini P, Vianello A, et al. Clinical and molecular characterization of patients with limb-girdle muscular dystrophy type 2I. Arch Neurol 2005; 62: 1894–1899. [DOI] [PubMed] [Google Scholar]
- 5.Fayssoil A, Ogna A, Chaffaut C, et al. Natural history of cardiac function in Duchenne and Becker muscular dystrophies on home mechanical ventilation. Medicine (Baltimore) 2018; 97: e11381. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Bourteel H, Vermersch P, Cuisset JM, et al. Clinical and mutational spectrum of limb-girdle muscular dystrophy type 2I in 11 French patients. J Neurol Neurosurg Psychiatry 2009; 80: 1405–1408. [DOI] [PubMed] [Google Scholar]
- 7.Dohna-Schwake C, Ragette R, Mellies U, et al. Respiratory function in congenital muscular dystrophy and limb girdle muscular dystrophy 2I. Neurology 2004; 62: 513–514. [DOI] [PubMed] [Google Scholar]
- 8.Catanzarite V, Gambling D, Bird LM, et al. Respiratory compromise after MgSO4 therapy for preterm labor in a woman with myotonic dystrophy: a case report. J Reprod Med 2008; 53: 220–222. [PubMed] [Google Scholar]